The invention generally relates to seals for use in trocar sleeves.
More specifically, the invention relates to a seal for a trocar sleeve, comprising a sealing body which, in the direction of a longitudinal centre axis of the sealing body, has a first axial end and a second axial end and, between the first and second ends, an elastic sealing element which, in a radially inner area relative to the longitudinal centre axis, defines a passage for an instrument.
The invention further relates to a trocar sleeve provided with such a seal.
Trocars are used in the medical field in the context of minimally invasive surgery for introducing instruments into the human or animal body. In a minimally invasive surgical procedure, a trocar, generally consisting of a trocar sleeve and of a trocar mandrel received in the trocar sleeve, is first used to create a minimally invasive access route into a body cavity. For this purpose, the trocar is pushed with the aid of the trocar mandrel through the skin and into the body. The trocar mandrel is then withdrawn from the trocar sleeve, while the trocar sleeve is left in position in the access that has now been created. Instruments such as endoscopes, forceps, scissors, suturing tools and the like for carrying out surgical measures can now be introduced through the trocar sleeve and into the body cavity.
Several instruments with different shaft diameters are often needed during an operation. The trocar sleeve must therefore be designed accordingly for insertion of these instruments.
A further requirement of a trocar sleeve is that it seals off the body cavity from the outside when the trocar sleeve has been introduced into the body and an instrument has been introduced through the trocar sleeve. This is important particularly for use of a trocar sleeve in laparoscopy, in which the body cavity, here the abdominal space, is insufflated with a gas in order to expand the body cavity (pneumoperitoneum).
In order to seal the body cavity off from the outside when an instrument has been introduced through the trocar sleeve, such trocar sleeves comprise, in the area of the trocar head, a seal through which the respective instrument is guided. The seal for this purpose comprises an elastic sealing element that bears sealingly around the circumference of the shaft of the instrument that has been introduced.
However, since different instruments with different shaft diameters are intended to be introduced through the trocar sleeve, the seal present in the trocar sleeve must also ensure sealing for different shaft diameters of the inserted instruments. It will be appreciated that the internal diameter of the sealing element, which defines the passage for the instrument, has to be designed for the smallest shaft diameter of an instrument, so as to ensure sealing for this thin instrument too.
However, in order also to permit the introduction of instruments with a greater shaft diameter, the sealing element must possess a sufficient radially elastic extensibility. For this purpose, the presently known seals comprise sealing elements that have very thin walls. This is particularly the case of a seal known from the document DE 692 04 958 T2.
This known seal comprises a sealing element having the shape of an hourglass. The sealing element has converging and diverging side walls that form the passage for an instrument at their point of intersection. The outer ends of the seal are formed by flange sections. Said document proposes increasing the internal diameter of the passage by applying a vacuum or a negative pressure to the outside of the sealing element. However, producing a trocar sleeve seal to which a vacuum can be applied is technically complex and therefore disadvantageous.
A further disadvantage of the abovementioned thin-walled sealing elements of the known seals is that the thin wall of the sealing element can already be damaged upon initial contact with pointed, sharp or hook-shaped instruments.
A further disadvantage is that instruments with smaller shaft diameters are poorly guided in the seal.
Moreover, the sealing action of the known seals is often lost when the instrument guided through the trocar sleeve is moved sideways, i.e. transverse to the shaft direction, or tilted. Because of the poor lateral hold of the thin-walled sealing elements, a sideways movement causes the contact between the sealing element and the instrument shaft to be lost around part of the circumference of the instrument shaft, as a result of which sufficient sealing is then no longer guaranteed.
A seal known from the document DE 37 37 121 A1 also comprises a thin-walled sealing element, wherein the sealing element has a hollow space which is filled with a gaseous or liquid medium in order to narrow the passage for the instruments to be sealed, in order to obtain the desired sealing effect. This known seal thus requires an increased pressure in the hollow space of the sealing element for obtaining the sealing effect, which increased pressure is obtained by supplying a liquid or a gas into the hollow space. The disadvantage is that the trocar has to be connected with a pressure source via one or several lines during a surgical operation, which may represent an obstacle to the physician during a surgical operation. Furthermore, the expenditure in terms of additional equipment for supplying pressure to the sealing element is increased in disadvantageous fashion.